dehumidification kiln drying schedules

Regardless of size, allow for a 36 door that opens to a hallway of open space. Academia.edu no longer supports Internet Explorer. Culm parts with 2.0 and 2.2 m length after pressure treatment were dried in industrial kilns using three schedules with mild, severe and highly severe drying intensity. Changing the position of the doorway in various kiln setups helps provide the best access to the stacks of lumber. Use the gridded drawings provided on the PDF, Woodworking | Blog | Videos | Plans | How To. Case hardening is a defect caused by the outer portion of a board drying quickly, while the inner portion dries more slowly. A small "m" after the designation indicates that the wet-bulb temperatures should be adjusted to avoid temperatures below 90 F. See the above mentioned publication for details. Take a moisture reading in the end grain with a pin-type moisture meter or remote probe.) Many available kiln designs require a large, heavy door. The schedule designations use the popular U.S. Forest Products Laboratory designations. Please refer to Appendix A which shows the Lumber Dry Kiln Bill of Materials. USDA, 1991) . Sears Canada 70 Pint Dehumidifier. Lock For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. Forum Responses (See the following sections for a discussion of how to develop a schedule from these designations.) This makes lightweight baffles that can be easily moved and repositioned. The DH is not needed at this time, as the lumber is already bone-dry. Official websites use .gov They are easy to use and give you precision control over your drying. If we revisit the example of a $1,300 gross savings from a load of 540 BF of white oak lumber, and we subtract the estimated cost of $62 to kiln dry the lumber, we arrive at a net savings of $1,238 less than retail. (I have found that remotely monitoring the temperature and humidity with a WiFi sensor can be very helpful. Drying lumber too quickly can lead to deep end checking, warping and case hardening. A dehumidification kiln makes sense particularly when the lumber is air-dried first. 5. The baffles direct airflow over and through the stack and prevent the top layers from drying too quickly. Vacuum Kiln Drying. /Filter /JBIG2Decode If you cannot find exact match, look at SG of same family species. endstream endobj 283 0 obj <>/Metadata 40 0 R/OCProperties<>/OCGs[294 0 R]>>/Outlines 53 0 R/PageLayout/SinglePage/Pages 280 0 R/StructTreeRoot 72 0 R/Type/Catalog>> endobj 284 0 obj <>/Font<>/Properties<>/XObject<>>>/Rotate 0/StructParents 0/Tabs/S/Type/Page>> endobj 285 0 obj <>stream This limits the amount of energy needed to bring lumber to the desired 6% to 8% moisture content. This gives me a secondary method of tracking the drying process, using both water volume and moisture content (MC) readings. I had these custom cut and I air dried them outside under a tarp for 6 to 18 months (depending on which load they came in on) and then I kiln dried them in a Nyle dehumidification kiln for 3 months. Schedule for drying 4/4 and 5/4 upland red oak in a steam dry kiln. However, you may need more cycles depending on the species, moisture content, and size of the timber. Recently, either Wood, or American Woodworker showed how to build a small version of a solar kiln. This problem is magnified if the lumber is thin or flatsawn. Saving money by drying your lumber may not be the answer for every woodworker, but the basics shown here demonstrate that it is within the reach and skills of the average person. Many articles have been dedicated to solar lumber kilns: everything from a simple sheet of Visqueen over a stack of lumber in the sunshine to elaborate enclosures designed for solar gain. John Baines Reply to Dann Barry 1 year ago A small electric heater supplies auxiliary heat to maintain adequate kiln temperature. This would allow a stack of lumber four feet wide and 10 feet long. Rep. FPL-GTR-57. Page 30 Wood-Mizer Figure 3-4 Drying Schedules Normal Schedule Alternate Schedule Moisture Content Dry Bulb Wet Bulb Dry Bulb Wet Bulb Group 2 Above 45% 90F 85F 100F 97F . November 1, 2020. . Determine the correct designation, such as T3-D2 for 4/4 red oak. Usually, you need anywhere between five to eight kiln schedules to complete the process. Among dimension lumber, the 2- by 4-inch size is typically the most susceptible to warp for a variety of reasons. The conversion method described in the Dry Kiln Operator's Manual is not really accurate, but it is safe. An anemometer confirms that your effort constructing baffles was worthwhile. In addition, weight on top of the stack can be helpful, but nothing replaces baffles for the best lumber yield. Wood poles subjected to a 22- to 34-day dehumidification kiln schedule with a heat treatment to 60C to the poles' core. Once all the lumber is stacked and stickered, place baffles over the lumber. In the majority of cases, the drying schedules are from the world literature, with emphasis on U.S., Canadian, and British publications. The company's small kilns can be configured for drying lumber, firewood, or heat-treating lumber or wood packaging. An official website of the United States government. Rocky Mountain . Gen. Tech. But kiln drying may also introduce internal stresses into the woodparticularly if an improper kiln schedule is used, . Place some sample boards in the stack that will be easy to pull out for moisture testing later. Soon the DH wont show much water collected in the tray. I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. 0000006297 00000 n Check out More On the Web for my complete calculations to figure savings. In vacuum kiln trials, logs were heated to 56C at 70 percent log radius depth and the temperature maintained for . On this order alone, I saved over $1,300 by drying the lumber myself. << Just walk out to the shed kiln and grab what you need from your custom-dried supply. Dehumidification drying system. A better choice might be a solar kiln, as you can dry wood from "wet" to 6-8 percent MC in 6-8 weeks. Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. Low temperatures can be used for an extra safety margin on greener lumber. Wood Shrink/Swell estimator - A web-based program to estimate shrink/ swell in wood. stream Looking at the cost-benefit analysis of a shed kiln can be enlightening. Formulating a Kiln Schedule These are rough-saw red oak. This helps keep the lumber straight during the drying cycle; in fact, improper placement of stickers can permanently deform lumber. 9. Dehumidification Kiln. Built properly, a shed kiln may even increase the value of a property. Share. In the fourth column, write down the wet-bulb depressions (determined in #4 above), one for each Schedule Step, starting at the top (Schedule Step 1). building the dehumidification dry kiln. Share sensitive information only on official, secure websites. However, if you kiln dry hardwood lumber that has already been air dried, the process is much more forgiving. I also wrapped the shed with Tyvek HomeWrap. If required, look-up and write down the RH (sixth column) and EMC (seventh column) for each schedule step. ) or https:// means youve safely connected to the .gov website. A lower RH setting will call for the DH to run more often. The second most common type of drying is called dehumidification drying. Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. A lazy Susan with 180 detents mounts the fan box to the ceiling. Our approach was to build and operate a small dehumidification dry kiln. Always use adequate samples representing both the wettest and driest lumber in the dryer. A maximum 45 F depression often produces better lumber. Insulate the floor with 2 rigid foam for convenience and durability. Extruded polystyrene foam (blue or pink rigid foam) in this thickness has an R value of 10. Although dehumidification kilns are slower than conventional kilns for drying, the lower drying temperature has the reported advantage of less degrade and less shrinkage. I found that brackets for mounting rigid metal electrical conduit work best. Without baffles, the top layers of lumber experience "potato chipping" with cupping, twisting or warping. Subtract the wet-bulb depression from the dry-bulb temperatures for each schedule step and enter the value in the fifth column. After a short period of grumbling, they join me to lay down wood blocks for the first layer of lumber. Perhaps the best part: you wont need to calculate your lumber needs down to the board foot. Also, you can't really control well by measuring the collected water because some of the water leaks out with vented or leaking air. For equalizing, use an EMC 2% below the target MC at a dry-bulb of 170 F. For conditioning, use an EMC 4% above the target MC at a dry-bulb of 180 F. Professor Gene Wengert is Extension Specialist in Wood Processing at the Department of Forestry, University of Wisconsin-Madison. Every Nyle Dehumidification Dry Kiln System Example: If the WBT falls below the set parameter measures and regulates internal kiln conditions the system will turn on the spray system. How do I convert from the standard kiln schedules in the USDA's "Dry Kiln Schedules for Commercial Woods" and "Drying Hardwood Lumber" to an SDR-type schedule? In the third column, write down the appropriate dry-bulb temperatures. This fact sheet summarizes the basics of kiln drying wood, the most commonly used methods, drying schedules and some drying defects. %PDF-1.6 % . I find that unplugging the DH is helpful during the sterilization phase so I can add a second heater, without overwhelming my electrical circuit. If it isn't overheating, it is leaking. Consider the weight of the lumber that will be placed in the structure and fortify the building accordingly. I made a simple frame from plywood strips and attached the insulation sheets to them with screws and fender washers. This slows the end-grain drying and limits the severity of end checking. This makes lightweight baffles that can be easily moved and repositioned. Dehumidification drying equipment is available, but an enclosure must be built to house the equipment and dry the lumber. The kiln humidity can be expressed as an EMC, relative humidity, or wet-bulb temperature. Changes in kiln temperatures and humidities are based on the MC of the lumber being dried, which in turn is determined from properly prepared kiln samples. Appendix B . The dry kiln operator is fully in control, with the ability to make changes as the dry kiln schedule is executing.